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Re: RAID implementation standards for Oracle

From: Gaja Krishna Vaidyanatha <gajav_at_yahoo.com>
Date: Fri, 15 Sep 2000 06:32:59 -0700 (PDT)
Message-Id: <10620.117098@fatcity.com>


Sean,

In the past 5 years, I have focussed on the I/O configuration and design aspect for Oracle and have done some extensive studying, benchmarking and implementation. The details are in the paper - "Impelementing RAID on Oracle", that I will be presenting at OOW 2000. I have however included my comments below. Hope it helps.

Best Regards,

Gaja

If you are the SA and the DBA or have a very tight relationship and a process defined with the SA, for mirror failure reporting, then hardware-level mirroring (RAID 1) could be OK.

> Data and Index RAID 10 For high write capacity.
> RAID 1 Moderate write
> capacity.
> RAID 5 Moderate write,
> heavy read.
> RAID 0 Best write
> performance but no fault tolerance!
>

I'd probably qualify RAID 5 as "Low Write", even in the presence of disk caches, as the parity overhead experienced by the I/O sub-system, which is dependent on the amount of write activity, can saturate the disk cache in a hurry. In my personal experience, I have seen this even on storage systems with disk caches of 20 - 32 Gb. Also, I'd add RAID 3 for low write and sequential read access patterns. RAID 5 is better suited for low write and random read access patterns.

Another point here is that the DATA tablespace should be in a volume supported by physical drives, independent of the INDX tablespace. Just because one is using RAID, one should not give up the separation of these two components. Although RAID 10 is a slightly different implementation of RAID 1+0, I'd mention 1+0 as it is more prevelant. This is true for all of the following sections, where relevant. Also, 1+0 should be always preferred over 0+1, as it facilitates better availability.

> SYSTEM TS RAID 10
> RAID 1
> RAID 5
> RAID 0
>

OK.

> RBS RAID 10
> RAID 1
> RAID 5
> RAID 0
>

OK.

> TEMP RAID 10 If little loss of
> functionality due to loss of TEMP
> RAID 1 and can be easily
> relocated then consider RAID 0
> RAID 5
> RAID 0
>

OK.

> Archive Logs RAID 5
> RAID 10 For high change
> activity.
>

I personally prefer Archive Logs on RAID 1+0 first, RAID 5 would be my last choice. If I had it my way, I'd prefer RAID 3 over RAID 5 for this since there only ARCH is writing to this device and it is bulk and sequential in nature.

> Control Files Non-specific Always mirror at
> Oracle-level
>

OK.

> Oracle Software
> and
> Configuration
> Files RAID 1
>
>

OK.



Gaja Krishna Vaidyanatha
Director, Storage Management Products, Quest Software Inc. Office : (972)-304-1170, E-mail : gajav_at_yahoo.com

Author - Oracle Tuning 101 by Osborne McGraw-Hill "Opinions and views expressed are my own and not of Quest"


Received on Fri Sep 15 2000 - 08:32:59 CDT

Original text of this message

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